Motorola scientists have figured out how to get bring silicon, the basis of commodity semiconductor chips, and gallium arsenide, used to make expensive, high-performance parts, to co-exist on the same device. The move paves the way for cheap chips that combine electronic and optical connections, the company reckons.

Actually, they figured it out some time ago - 1998, to be exact - but it has taken the intervening years to turn the principle into a process chip manufacturers can use.

Essentially, that process involves placing a layer of an intermediate compound between the layers of silicon and gallium arsenide. The upshot is a part that's able to run at up to 40 times the speed of regular silicon circuitry, yet maintains the rugged nature of ordinary silicon chips. Gallium arsenide chips have been around for some time, but they are delicate and hard to produce.

The technique can be applied to other materials with the same properties as gallium arsenide, such as indium phosphide. Together, these compounds are called III-V semiconductors.

III-V materials have a different crystalline structure to regular silicon, making it almost impossible to bond the two together without damaging the crystal lattices of both compounds. Motorola's breakthrough was to find a material that can bond with both.

Motorola has already produced 8in and 12in wafers containing chips built out of both silicon and gallium arsenide, and it hopes to start offering parts based on the new process "within a year or so". It already reckons that a silicon-gallium arsenide chip costs about a tenth of what a pure gallium arsenide device costs to make.

The company has already filed 270 patents relating to the nature and usage of the technology, and - surprise, surprise - has begun sniffing out potential licensees. It has a long list to choose from: practically everyone in the chip business is likely to be very keen to get their hands on the technology.

That may not please Motorola's own chip-making operation, the loss-making Semiconductor Products Sector, which appears not to have been the source of the work - Motorola Labs has that honour. That allows Motorola to hang on to the technology should it subsequently sell or spin off SPS, a move the company has said it will make if the chip operation doesn't pull its socks up. ®